1. Field of the Invention
The present invention pertains to wrenches and more particularly to a self-adjusting wrench.
2. Discussion of Related Art
Various wrenches are known. Some wrenches are closed-end wrenches, that is wrenches that encompass the circumference of a workpiece. In some circumstances, due to tight working quarters for example, use of a closed-end wrench to drive a workpiece may be precluded. As an alternative to a closed-end wrench, an open-ended wrench may be used.
While some designs for open-ended wrenches are available, these designs have some limitations.
FIG. 1 is an elevational view of a conventional open-end wrench. As shown in FIG. 1, conventional open-end wrench 10 has a handle 11 and two containing parts 12 on both sides of handle 11. Each containing part 12 has a containing groove 13 for receiving a nut-locking component 20, and two jaws 14, one jaw 14 on each side of containing groove 13.
When operated, open-end wrench 10 can be applied to nut-locking component 20. The containing groove 13 engages external surface of the nut-locking component 20 such that the two opposite containing surfaces 141 between the two jaws 14 are brought in contact with two symmetrical outer surfaces 21 of the nut-locking component 20. By applying a torque to the handle 11 of the wrench 10 to rotate the wrench 10, the nut-locking component 20 will rotate accordingly. Although the open-end wrench 10 provides the function of rotating the nut-locking component 20, it has the following deficiencies.
Because the working space to complete a full rotation 360° of the wrench 10 may be limited, the nut-locking component 20 may not complete a full rotation. Hence, after open-end wrench 10 rotates nut-locking component 20 to an intended position in one direction, the wrench 10 has to be removed from the nut-locking component 20 and rotated in the opposite direction in order to continue rotating nut-locking component 20 in the initial direction. Because the two jaws 14 are fixed, the open-end wrench 10 should be disconnected from nut-locking component 20 before rotating the wrench 10 in the opposite direction so as not to drive nut-locking component 20 to rotate in the opposite direction. Once the jaws 14 are brought again in contact against the two opposite surfaces 21, the rotation of nut-locking component 20 can be resumed. Therefore, the wrench 10 can be inconvenient to use.
Furthermore, when the open-end wrench 10 is applied to the nut-locking component 20, the two symmetrical outer surfaces 21 of nut-locking component 20 are held between the two parallel containing surfaces 141 in the containing groove 13 of the open-end wrench 10. Therefore, when the wrench is applied to the nut-locking component 20 whose size (a distance between the two opposite surfaces 21) is smaller than a distance between the two parallel containing surfaces 141, each of the two containing surfaces 141 forms an angle relative to each of the two surfaces 21 of nut-locking component 20. When a torque is exerted on open-end wrench 10 to rotate nut-locking component 20, the nut-locking component 20 can sometimes be stripped.